The invention relates to a device for mounting a microphone built into portable or movable audio equipment, for example a tape recorder or a combination radio receiver and cassette recorder commonly called a radio cassette recorder. Recording equipment of this type normally includes transport mechanisms, for example a motor and transmissions which have pulleys and rollers and/or gears so as to transport the material which stores the audio information, in particular a magnetic tape.
In known tape recorders or radio-cassette combinations which include a built-in microphone, the microphone is mounted at the inside of the front or top wall of the enclosure of the mechanism with the aid of a support fixture which normally surrounds the microphone and holds it in place with the aid of fingers that are attached by screws to threaded holes in the enclosure. Such supports or fixtures are described for example in the U.S. Pat. No. 3,947,646 or the French Pat. No. 2,210,071. They are configured to hold or surround the generally cylindrical microphone and are made of metal or plastic in the form of sheet metal plates or thin foils so as to have a very high acoustic impedance. They may also be made of natural or synthetic rubber of varying degrees of rigidity and elasticity so as to attenuate as much as possible any mechanical vibrations which are transmitted to the chassis and to the cabinet supporting it from the drive motor and other components of the tape transport mechanism. If the microphone mount is made from an elastic material, it will constitute, together with the microphone, a resonant mechanical system whose natural resonance frequency must lie below the low cut-off frequency of the microphone, i.e., approximately 10 Hz. Such a condition is almost impossible to fulfill due to the fact that the microphones used in portable recorders usually have very low mass, whether they are electret microphones or other types.